Matthew Quigley and Pakee Ristine in the photo they both used as their profile picture on Facebook.

The 2010 Riverhead High School graduate killed in a car accident in South Carolina Saturday was a “sweetheart” who was looking forward to returning home to Long Island with his girlfriend to become a father, school and funeral home officials said Tuesday.

“They were planning on having a baby together, planning to spend their lives together,” said Ken Rothwell, director at the Alexander-Tuthill Funeral Home in Wading River.

Matthew Quigley, 20, was driving on I-95 Saturday morning with his girlfriend, Pakee Ristine, 19, of Mastic Beach, when a U-Haul trailer attached to his truck came loose and he lost control of his vehicle, the South Carolina Highway Patrol said.

Mr. Quigley, and Ms. Ristine were ejected from the 2005 Chevy Trailblazer after the truck hit the median and overturned shortly before noon, officials said. Mr. Quigley was killed in the crash.

He is survived by his mother, Heidi Watson-Wold, his stepfather, Eric Wold, both of Wading River, and his father, Joseph Quigley of Florida.

Ms. Ristine, a 2011 graduate of William Floyd High School, is in serious condition at a Columbia, S.C. hospital, a hospital spokesperson said.

Ms. Ristine was pregnant with the couple’s child at the time of the accident, Mr. Rothwell said; the baby did not survive the accident and Ms. Ristine is “not doing well,” he said.

“We’re praying for her recovery,” Mr. Rothwell said.

Mr. Quigley studied marine mechanics at BOCES during his time at the High School, district administrators said.

He had just graduated from the Marine Mechanics Institute in Orlando, Fla. on Friday and was returning to Long Island with Ms. Ristine.

“He was a real sweetheart of a kid,” said Riverhead High School principal David Wicks. “Great in his field.”

Ms. Watson-Wold declined to speak to reporters when reached by phone Tuesday, saying she had already spoken to a local news outlet and wished to not comment further.

“He was just such a good kid,” Ms. Watson-Wold said in the interview with RiverheadLOCAL.com. “You have to ask, why? Why?”

Visiting hours for Mr. Quigley will take place Wednesday, Oct. 24, from 2 to 4 and 6 to 8 p.m. at Alexander-Tuthill Funeral Home in Wading River, immediately followed by a prayer service at 8 p.m. Cremation will be private.

In lieu of flowers, donations may be made to SoundWaters.org., an organization dedicated to educating children and adults about Long Island Sound and its watershed.